The embodiments described herein relate to transducer structures, and more particularly, to methods and systems for a controlled formation and arrangement of a transducer structure for use in transducer probes.
Ultrasonic probes, which often include a piezoelectric post or an array of piezoelectric posts, are used in several applications, including the nondestructive imaging of the interior of structures by, for instance, ultrasound scanning. In many such imaging applications, it is desirable to use a composite material, which is usually comprised of a piezoelectric material and a non piezoelectric material. These composite materials result in better piezoelectric performance as compared to monolithic piezoelectric materials. It is necessary to reduce the size of the individual piezoelectric features, which constitute the composite, as much as possible, to enable operation at higher frequencies, which in turn provides increased resolution in the obtained image. Known dice-and-fill methods for manufacturing piezoelectric transducers generally reach a resolution limit when columnar posts in the piezoelectric transducers are reduced in size. Moreover, known methods of manufacturing probes, such as dice-and-fill methods, are limited to the fabrication of straight line kerfs between transducer posts, thereby restricting the available transducer design space, e.g. limits of transducer post arrangements, cross-sectional shapes and the inability to make free-form three-dimensional transducer features.
Operation of known ultrasound probes at higher frequencies is achieved in part by decreasing the thickness of the transducer material and correspondingly reducing the x-y cross-sectional area of the piezoelectric posts comprising the transducer. This operation results in an increase in the dicing time to complete the manufacturing of the transducer. Moreover, the production yield of the dice-and-fill method for manufacturing high-frequency transducers is generally reduced as compared to the production yield of conventionally manufactured lower-frequency transducers due to the increased likelihood of breakage of the (thinner) piezoelectric posts. Additionally, known manufacturing methods may produce transducers fabricated with shear waves that cause one or more ultrasound wavelengths to travel within the composite structure. Shear waves result in design constraints for probes and result in acoustical interferences such as ringing in probes.